hdu 2732 最大流 **

  1 //============================================================================
  2 // Name        : HDU.cpp
  3 // Author      : 
  4 // Version     :
  5 // Copyright   : Your copyright notice
  6 // Description : Hello World in C++, Ansi-style
  7 //============================================================================
  8 
  9 #include <iostream>
 10 #include <string.h>
 11 #include <stdio.h>
 12 #include <algorithm>
 13 using namespace std;
 14 
 15 const int MAXN=2200;
 16 const int MAXM=200020;
 17 const int INF=0x3f3f3f3f;
 18 struct Node
 19 {
 20     int to,next,cap;
 21 }edge[MAXM];//注意是MAXM
 22 int tol;
 23 int head[MAXN];
 24 int gap[MAXN],dis[MAXN],pre[MAXN],cur[MAXN];
 25 
 26 void init()
 27 {
 28     tol=0;
 29     memset(head,-1,sizeof(head));
 30 }
 31 void addedge(int u,int v,int w,int rw=0)
 32 {
 33     edge[tol].to=v;edge[tol].cap=w;edge[tol].next=head[u];head[u]=tol++;
 34     edge[tol].to=u;edge[tol].cap=rw;edge[tol].next=head[v];head[v]=tol++;
 35 }
 36 int sap(int start,int end,int nodenum)
 37 {
 38     memset(dis,0,sizeof(dis));
 39     memset(gap,0,sizeof(gap));
 40     memcpy(cur,head,sizeof(head));
 41     int u=pre[start]=start,maxflow=0,aug=-1;
 42     gap[0]=nodenum;
 43     while(dis[start]<nodenum)
 44     {
 45         loop:
 46         for(int &i=cur[u];i!=-1;i=edge[i].next)
 47         {
 48             int v=edge[i].to;
 49             if(edge[i].cap&&dis[u]==dis[v]+1)
 50             {
 51                 if(aug==-1||aug>edge[i].cap)
 52                     aug=edge[i].cap;
 53                 pre[v]=u;
 54                 u=v;
 55                 if(v==end)
 56                 {
 57                     maxflow+=aug;
 58                     for(u=pre[u];v!=start;v=u,u=pre[u])
 59                     {
 60                         edge[cur[u]].cap-=aug;
 61                         edge[cur[u]^1].cap+=aug;
 62                     }
 63                     aug=-1;
 64                 }
 65                 goto loop;
 66             }
 67         }
 68         int mindis=nodenum;
 69         for(int i=head[u];i!=-1;i=edge[i].next)
 70         {
 71             int v=edge[i].to;
 72             if(edge[i].cap&&mindis>dis[v])
 73             {
 74                 cur[u]=i;
 75                 mindis=dis[v];
 76             }
 77         }
 78         if((--gap[dis[u]])==0)break;
 79         gap[dis[u]=mindis+1]++;
 80         u=pre[u];
 81     }
 82     return maxflow;
 83 }
 84 
 85 char g1[30][30];
 86 char g2[30][30];
 87 int mat[30][30];
 88 
 89 int main()
 90 {
 91     //freopen("in.txt","r",stdin);
 92     //freopen("out.txt","w",stdout);
 93     int T;
 94     int n,d;
 95     int iCase=0;
 96     scanf("%d",&T);
 97     while(T--)
 98     {
 99         iCase++;
100         scanf("%d%d",&n,&d);
101         init();
102         int tol=0;
103         for(int i=0;i<n;i++)
104             scanf("%s",&g1[i]);
105         int m=strlen(g1[0]);
106         memset(mat,0,sizeof(mat));
107         for(int i=0;i<n;i++)
108             for(int j=0;j<m;j++)
109                 if(g1[i][j]>‘0‘)
110                 {
111                     mat[i][j]=++tol;
112                     addedge(2*tol-1,2*tol,g1[i][j]-‘0‘);
113                 }
114 
115         int start=0,end=2*tol+1,nodenum=2*tol+2;
116         //进行拆点，加上源点和汇点，共2*tol+2个点。
117         int sum=0;//总数
118         for(int i=0;i<n;i++)
119         {
120             scanf("%s",&g2[i]);
121             for(int j=0;j<m;j++)
122                 if(g2[i][j]==‘L‘)
123                 {
124                     sum++;
125                     addedge(start,2*mat[i][j]-1,1);
126                 }
127         }
128         for(int i=0;i<n;i++)
129             for(int j=0;j<m;j++)
130                 if(mat[i][j])
131                 {
132                     for(int x=-d;x<=d;x++)
133                         for(int y=abs(x)-d;y<=d-abs(x);y++)
134                         {
135                             int newi=i+x;
136                             int newj=j+y;
137                             if(newi<0||newi>=n||newj<0||newj>=m)continue;
138                             if(mat[newi][newj]==0)continue;
139                             if(newi==i&&newj==j)continue;
140                             addedge(2*mat[i][j],2*mat[newi][newj]-1,INF);
141                         }
142                     if(i<d||j<d||n-i<=d||m-j<=d)
143                         addedge(2*mat[i][j],end,INF);
144                 }
145         int ans=sum-sap(start,end,nodenum);
146         if(ans==0)printf("Case #%d: no lizard was left behind.\n",iCase);
147         else if(ans==1)printf("Case #%d: 1 lizard was left behind.\n",iCase);
148         else printf("Case #%d: %d lizards were left behind.\n",iCase,ans);
149     }
150     return 0;
151 }